This application relates generally to the field of computer networks. More specifically, the disclosure provided herein relates to passively inferring a Transmission Control Protocol (“TCP”) initial congestion window (“ICW”).
Modern Internet Protocol (“IP”) networks carry traffic from a diverse set of applications, ranging from non-real-time applications to real-time applications. Generally, real-time applications are those applications that meet a real-time constraint, i.e., a time limit in which a system responds to a request or event. Examples of non-real-time applications include email and bulk data transfers (e.g., File Transfer Protocol (“FTP”) file transfers). Examples of real-time applications include Voice over IP (“VoIP”), Internet Protocol Television (“IPTV”), Internet games, and critical business transactions.
Historically, non-real-time applications dominated the Internet landscape. However, in recent years, real-time applications have become increasingly popular. A number of factors have contributed to this material shift from non-real-time applications to real-time applications. These factors include the rapid deployment of backbone links with one to two orders of magnitude more network capacity, the increasing reach of broadband access networks, the emergence of bandwidth-intensive streaming applications, and an economic and technological move towards transitioning even mission-critical applications from dedicated networks to the Internet through architectures like Virtual Private Networks (“VPNs”).
While the applications, as well as the constraints upon which the applications operate, have multiplied, TCP has remained the dominant transport layer protocol in IP networks. In particular, TCP is widely adopted by many new applications and accounts for the majority of current traffic on the Internet. However, TCP was originally designed to support a reliable, in-order delivery of a byte stream between two endpoints in a bandwidth friendly manner. In this regard, TCP is not an ideal transport protocol for real-time applications.
A number of considerations have contributed to the dominance of TCP in IP networks. These considerations include the following: (1) TCP is deployed nearly ubiquitously; (2) TCP helps offload many low-level transport details with which an application developer would otherwise have to contend; and (3) TCP packets are routinely allowed by firewalls, which typically block non-TCP data flows. Further, fueled by the need to support more stringent performance requirements of emerging applications, developers have created various TCP variants, such as FAST, HSTCP, and CUBIC. Some vendors have also promoted acceleration hardware that offers propriety optimizations to TCP.
While TCP continues to dominate IP networks, little is known or studied about the behavior of TCP traffic on the Internet. Understanding the behavior of TCP may be vital for proper management, provisioning, and capacity planning of IP networks. Further, understanding the behavior of TCP may provide insights to guide network protocol design.